Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 131131
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
531 AM CST Thu Dec 13 2018

.DISCUSSION...
12Z TAFs.

&&

.AVIATION...
Wind, areas of MVFR conditions and areas of rain will be issues
to aviation today and tonight. Patchy IFR ceilings will also occur
at some locations. Cold front is moving into northwest Oklahoma
with winds shifting to northerly behind the front. Although winds
pick up with the frontal passage, winds will increase further a
couple of hours after the front. Most areas will see gusts over 35
knots and many areas in western Oklahoma and western north Texas
will have gusts over 45 knots. The wind will not decrease much
after sunset and will stay gusty.


&&

.PREV DISCUSSION... /issued 513 AM CST Thu Dec 13 2018/

DISCUSSION...
The primary forecast issue is the impacts for today`s system,
including strong, potentially damaging wind gusts along with
widespread rainfall.

A closed-low across south New Mexico will move east-southeastward
into the Big County of Texas today. The attendant surface cyclone
is forecast to move eastward along with a cold front. Strong
northerly winds are expected behind this cold front due to a tight
surface pressure gradient and attendant ~5+ mb/3 hr surface
pressure rises. Progged surface pressure gradient across southwest
Oklahoma is ~ 5 mb/145 km at 00Z today , which is significant.
BUFKIT soundings indicate the potential for wind gusts over 60
mph, especially across southwest Oklahoma. Convective-allowing
models (e.g., 3 KM NAM and HRRR) wind gust forecasts agree with
this as well. There are indications that wind gusts near High Wind
Warning criteria (58 mph) may even occur farther east into south
central Oklahoma. This trend will have to be monitored today. The
bottom line: the wind will the most impactful part of this storm
system!

These strong winds will continue into this evening with a gradual
weakening late tonight. Gusty, northerly winds (though weaker)
will remain possible through at least the first half of Friday--so
a Wind Advisory is in effect far the southern half of Oklahoma
and western north Texas through noon Friday.

Along with the wind, widespread rainfall is expected. Isentropic
ascent ahead of the closed-low will result in development of rain
ahead of the wave. Showers and isolated storms have already
developed across eastern Oklahoma this morning. As the upper-level
low deepens and ascent wraps around it, rain will develop north
and west of the cyclone. Elevated instability indicates thunder
will be possible, especially southeast of I-44 and east of I-35.
Convective-allowing models indicate a cellular/convective
appearance to some reflectivity as well. Therefore, opted to add a
mention of thunder. In addition, precipitable water values are
forecast to be >= 1.00" (>90th percentile per SPC Sounding
Climatology) across south central and southeast Oklahoma, so some
of the convective cells could have heavy rainfall.

With the track of the upper-level low to the south of the area,
the greatest risk for accumulating snow will be across the Big
Country of Texas, where temperatures aloft will be coldest (south
of Knox, Baylor, Archer, and Clay counties). In addition, with the
system slowing down and deepening, warmer (>0C) air forecast to
wrap farther to the west along the north side of the upper-level
low with east-northeast to northeasterly flow at low-levels (e.g.,
850 mb). This decreases the chance of snow immediately north of
the upper-level low track (with the greater potential to the west
to west-northwest of the low). Some snow may still mix with rain
into parts of Knox and Baylor counties (with even lower potential
in Archer and Clay counties), but significant accumulations are
not likely. Therefore, the Winter Storm Watch was canceled. This
will have to monitored throughout the day as any shift farther
north may require a Winter Weather Advisory.

With the system closing off/slowing down, lingering precipitation
and cloud cover will continue into Friday with a cool and breezy
day. Seasonably warmer weather (highs in the mid 50s to near 60 F)
is expected for the upcoming weekend with dry conditions. The
quiet and mild weather is expected to continue through early next
week with perhaps a chance of rain by the middle part of next
week.

Mahale

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  47  33  46  29 /  90  70  30  10
Hobart OK         47  32  50  28 /  50  30  10   0
Wichita Falls TX  50  36  50  31 /  90  80  40   0
Gage OK           46  24  50  23 /  10   0   0   0
Ponca City OK     47  32  47  27 /  70  60  20  10
Durant OK         60  39  46  35 /  90  90  70  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Wind Advisory from 9 AM this morning to 6 AM CST Friday for
     OKZ007-008-012-013-018>020-024>026.

     High Wind Warning until 6 AM CST Friday for OKZ004>006-009>011-
     014>017-021>023-027-033>039-044-045.

     Wind Advisory from 6 AM to noon CST Friday for OKZ021>023-027-
     033>039-044-045.

     Wind Advisory from 3 PM this afternoon to noon CST Friday for
     OKZ030>032-040>043-046>048-050>052.

     Wind Advisory from 9 AM this morning to noon CST Friday for
     OKZ028-029.

TX...High Wind Warning until 6 AM CST Friday for TXZ083>090.

     Wind Advisory from 6 AM to noon CST Friday for TXZ083>090.

&&

$$


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